mkj-gram

# Keep the class that is reflected on and its methods.
-keep,allowobfuscation class ReflectOnMe {
  <methods>;
}

# Keep kotlin.Metadata annotations to maintain metadata on kept items.
-keepattributes RuntimeVisibleAnnotations
-keep class kotlin.Metadata { *; }

mkj-gram

class ReflectOnMe() {
    fun String.extension(): String {
        return capitalize()
    }
}

fun reflect(receiver: ReflectOnMe): String {
    return ReflectOnMe::class
        .declaredMemberExtensionFunctions
        .first()

mkj-gram

# Keep the D8CommandBuilder and all their methods.
-keep class com.example.mylibrary.D8CommandBuilder {
  <methods>;
}

# Keep the extension functions.
-keep class com.example.mylibrary.CommandBuilderKt {
  <methods>;
}

mkj-gram

package com.example.mylibrary
/** D8CommandBuilder to build a D8 command. */
class D8CommandBuilder: CommandBuilderBase() {
    internal var intermediateOutput: Boolean = false
    override fun getCommandName() = "d8"
    override fun getExtraArgs() = "--intermediate=$intermediateOutput"
}

fun D8CommandBuilder.setIntermediateOutput(intermediate: Boolean) : D8CommandBuilder {
    intermediateOutput = intermediate

mkj-gram

package com.example.mylibrary

/** CommandBuilderBase contains options common for D8 and R8. */
abstract class CommandBuilderBase {
    internal var minApi: Int = 0
    internal var inputs: MutableList<String> = mutableListOf()

    abstract fun getCommandName(): String
    abstract fun getExtraArgs(): String